technically, if a small amount of people own the lion's share of Steem Power, and they target you in an attempt to silence you for your opinion (as long as it wasn't against terms of service or various laws), then it could be said that you were in fact censored - despite the platform being decentralized.

It can be argued that this isn't censorship, but if the majority of steem power holders decided you were to be silenced for petty reasons, then I personally would call it censorship, no different than if YouTube decided to block your video or make it invisible. The only difference lies in culpability, and there would be little recourse but to leave the platform or start over.

It doesn't seem like that's the case here, as there are many reasons to down-vote someone. Being silenced is a good reason to leave any platform, regardless of how someone is accomplishing it, but in my mind Steem has much bigger issues than whales being dicks, and those problems will likely become apparent within the next year or so.